Generally, a lean burn engine is designed to produce the same power output as a conventional engine while consuming less fuel than the conventional engine. This is accomplished by forming a strong swirl of the intake air in the combustion chamber and injecting fuel therein for combustion.
Accordingly, an intake port that forms the strong swirl of air is required. The intake port typically constitutes a linear port and a swirl port. The linear port has a straight line-shape configuration and the swirl port has a curved-shape configuration to change the flow direction of the intake air. The linear port and swirl port are manufactured by individual cores and are used in the mold of the cylinder head of the engine.
An injector is typically placed in the intake manifold. However, a drawback of placing the injector in the manifold is that fuel economy is not maximized and toxic exhaust gas production is not minimized. Therefore, it would be advantageous to place the injector a predetermined distance from a valve surface to achieve better fuel economy and reduce toxic exhaust gas.